Triggered spark gap devices are arc discharge tubes which are utilized as high voltage switches. These tubes contain a pair of opposing dome electrodes, functioning as the contacts of the switch, which are spaced far enough apart to remain insulated from each other and maintain a potential difference of thousands of volts. A trigger electrode protrudes just through, and is insulated from, a hole in one of the dome electrodes. When the spark gap is to be switched, a trigger pulse is applied between the trigger electrode and the dome electrode through which it protrudes. This trigger pulse creates a spark, resulting in a breakdown or ionization of the gas contained within the tube, which then serves as a conductor between the two dome electrodes and effectively closes the switch.
The currently available trigger generating equipment is complex and usually only two to four spark gaps are triggered by a single trigger source.